FIG. 1 is a schematic diagram showing a state flow of a C1G2 compliant RFID tag in the prior art. The RFID tag is controlled by an RFID reader to enter different states. A plurality of states, namely a ready state, an arbitrate state, a reply state, an acknowledged state, an open state, a secured state and a killed state, are illustrated in FIG. 1. In the ready state, supposing the RFID tag is a passive RFID tag, it means that the RFID tag receives signals transmitted by the RFID reader and thus generates power. The RFID tag then receives a command of the RFID reader and enters the arbitrate state. A time-consuming and complex singulation procedure is necessarily performed to allow one selected RFID tag at a time to enter other states after the reply state, while other RFID tags await in the arbitrate state. In the acknowledged state, the RFID reader sends an identification code, such as “handle” in this example, for identification when the RFID reader accesses data.
Generally speaking, the ready, arbitrate, reply, and acknowledged phases are preparatory steps for accessing the RFID tag. After the open state and the secured state, the RFID tag enters an accessible stage including the open and secured states. In the open state, a part of a data stored in a first RFID tag is accessible. In the secured state, the RFID reader need be authorized by the first RFID tag before accessing more data than in an open state; that is, secured data is then accessible provided the RFID reader is authorized. Once having entered the killed state, the RFID tag remains in the killed state, in which the RFID tag is inaccessible. Referring to FIG. 1, the RFID tag directly enters the killed state from the open state by skipping the secured state. Detailed operations of accessing other C1G2 compliant RFID tags are known to a person having ordinary skill in the art, and thus shall not be discussed for brevity.
However, within a same round of accessing a group of RFID tags, the accessed RFID tags cannot be accessed again until the entire state flow is repeated. When data of another RFID tag is needed for accessing one of the RFID tags, the entire state flow is executed to access the RFID tag, and the accessed data is temporarily stored in other memory apparatuses. Again, the entire state flow is repeated to access a data of another apparatus when needed. Such methodology is rather inconvenient.